// Copyright 2016 Olivier Gillet. // // Author: Olivier Gillet (ol.gillet@gmail.com) // // Permission is hereby granted, free of charge, to any person obtaining a copy // of this software and associated documentation files (the "Software"), to deal // in the Software without restriction, including without limitation the rights // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell // copies of the Software, and to permit persons to whom the Software is // furnished to do so, subject to the following conditions: // // The above copyright notice and this permission notice shall be included in // all copies or substantial portions of the Software. // // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN // THE SOFTWARE. // // See http://creativecommons.org/licenses/MIT/ for more information. // // ----------------------------------------------------------------------------- // // Utility DSP routines. #ifndef PLAITS_DSP_DSP_H_ #define PLAITS_DSP_DSP_H_ #include "stmlib/stmlib.h" namespace plaits { static const float kSampleRate = 48000.0f; // There is no proper PLL for I2S, only a divider on the system clock to derive // the bit clock. // The division ratio is set to 47 (23 EVEN, 1 ODD) by the ST libraries. // // Bit clock = 72000000 / 47 = 1531.91 kHz // Frame clock = Bit clock / 32 = 47872.34 Hz // // That's only 4.6 cts of error, but we care! static const float kCorrectedSampleRate = 47872.34f; const float a0 = (440.0f / 8.0f) / kCorrectedSampleRate; const size_t kMaxBlockSize = 24; const size_t kBlockSize = 12; } // namespace plaits #endif // PLAITS_DSP_DSP_H_